1. Technical Field
The present disclosure relates to systems and methods for interfacing with high frequency data transfer media and, more particularly, to a modular jack housing insert assembly, such as those that are used as interface connectors for Unshielded Twisted Pair (“UTP”) media, that compensates for electrical noise.
2. Background Art
In data transmission, a signal originally transmitted through a data transfer media is not necessarily the signal received. The received signal will consist of the original signal after being modified by various distortions and additional unwanted signals that affect the original signal between transmission and reception. These distortions and unwanted signals are commonly and collectively referred to as “electrical noise,” or simply just “noise”. Noise is the primary limiting factor related to performance of a communication system. Many problems may arise from the existence of noise during data transmission, such as data errors, system malfunctions and loss of actual desired signals.
The transmission of data, by itself, generally causes unwanted noise. Such internally generated noise arises from electromagnetic energy that is induced by the electrical energy in the individual signal-carrying lines within the data transfer media and/or data transfer connecting devices, such electromagnetic energy radiating onto or toward adjacent lines in the same media or device. This cross coupling of electromagnetic energy (i.e., electromagnetic interference or EMI) from a “source” line to a “victim” line is generally referred to as “crosstalk.”
Most data transfer media consist of multiple pairs of lines bundled together. Communication systems typically incorporate many such media and connectors for data transfer. Thus, there inherently exists an opportunity for significant crosstalk interference.
Crosstalk can be categorized in one of two forms. Near end crosstalk, commonly referred to as NEXT, arises from the effects of near field capacitive (electrostatic) and inductive (magnetic) coupling between source and victim electrical transmissions. NEXT increases the additive noise at the receiver and therefore degrades the signal to noise ratio (SNR). NEXT is generally the most significant form of crosstalk because the high-energy signal from an adjacent line can induce relatively significant crosstalk into the primary signal. The other form of crosstalk is far end crosstalk, or FEXT, which arises due to capacitive and inductive coupling between the source and victim electrical devices at the far end (or opposite end) of the transmission path. FEXT is typically less of an issue because the far end interfering signal is attenuated as it traverses the loop.
A further particular distortion associated with high speed signal transmission is mismatch transmission impedances. Various interconnections occur as the signal travels down a transmission media. Each interconnection has its own internal impedance with respect to the traveling signal. For UTP cabling, the transmission media impedance is typically 100-Ohms. Offsets and/or differences from connecting devices will produce signal reflections. Signal reflections generally reduce the amount of signal energy transmitted to the receiver and distort the transmitted signal, which can lead to increased data bit loss.
Characteristics and parameters associated with electromagnetic energy waves can be derived by Maxwell's wave equations. In unbounded free space, a sinusoidal disturbance propagates as a transverse electromagnetic wave. This means that the electric field vectors are perpendicular to the magnetic field vectors lying in a plane perpendicular to the direction of the wave. As a result, crosstalk generally gives rise to a waveform shaped differently than the individual waveform(s) originally transmitted.
Unshielded Twisted Pair cable or UTP is a popular and widely used type of data transfer media. UTP is a very flexible, low cost media, and can be used for either voice or data communications. In UTP media, a pair of copper wires generally form the twisted pair. For example, a pair of copper wires with diameters of 0.4-0.8 mm may be twisted together and wrapped with a plastic coating to form a UTP cable. The twisting of the wires increases the noise immunity and reduces the bit error rate (BER) of the data transmission to some degree. Also, using two wires, rather than one, to carry each signal permits differential signaling to be used. Differential signaling is generally more immune to the effects of external electrical noise.
The non-use of cable shielding (e.g., a foil or braided metallic covering) in fabricating UTP media generally increases the effects of outside interference, but also results in reduced cost, size and installation time of the cable and associated connectors. Additionally, non-use of cable shielding in UTP fabrication generally eliminates the possibility of ground loops (i.e., current flowing in the shield because of the ground voltage at each end of the cable not being exactly the same). Ground loops may give rise to a current that induces interference within the cable, i.e., interference against which the shield was intended to protect.
The wide acceptance and use of UTP for data and voice transmission is primarily due to the large installed base, low cost and ease of new installation. Another important feature of UTP media is that it can be used for varied applications, such as for Ethernet, Token Ring, FDDI, ATM, EIA-232, ISDN, analog telephone (POTS), and other types of communication. This flexibility allows the same type of cable/system components (such as data jacks, plugs, cross-patch panels, and patch cables) to be used for an entire building, unlike shielded twisted pair (“STP”) media.
Currently, UTP is being used for systems having increasingly higher data rates. Since demands on networks using UTP systems (e.g., 100 Mbit/s and 1200 Mbit/s transmission rates) have increased, it has become necessary to develop industry standards for higher system bandwidth performance. Systems and installations that began as simple analog telephone service and low speed network systems have now become high speed data systems. As the speeds have increased, so too has the noise.
The ANSI/TIA/EIA 568A standard defines electrical performance for systems that utilize the 1 to 100 MHz frequency bandwidth range. Exemplary data systems that utilize the 1-100 MHz frequency bandwidth range include IEEE Token Ring, Ethernet 10Base-T and 100Base-T.
ANSI/TIA/EIA-568.2-10 and the subsequent ANSI/TIA/EIA-568B.2 standards define a series of categories, as shown in the following table, for quantifying the quality of the cable:
Characteristic specified upCategoryto X (MHz)Various Uses5100TP-PMD, SONet, OC-3(ATM), 100Base-TX5e10010-100BASE-T6250100-1000BASE-TX6A5001000-10GBASE-TX
UTP cable standards are also specified in the EIA/TIA-568 Commercial Building Telecommunications Wiring Standard, including the electrical and physical requirements for UTP, STP, coaxial cables and optical fiber cables. For UTP, the requirements currently include:                Four individually twisted pairs per cable;        Each pair has a characteristic impedance of 100 Ohms +/−15% (when measured at frequencies of 1 to 100 MHz); and        24 gauge (0.5106-mm-diameter) or optionally 22 gauge (0.6438-mm-diameter) copper conductors are used.        
Additionally, the ANSI/EIA/TIA-568 standard specifies the color coding, cable diameter, and other electrical characteristics, such as the maximum cross-talk (i.e., how much a signal in one pair interferes with the signal in another pair—through capacitive, inductive, and other types of coupling). Since this functional property is measured as how many decibels (dB) quieter the induced signal is than the original interfering signal, larger numbers reflect better performance.
Category 5 cabling systems generally provide adequate NEXT margins to allow for the high NEXT associated with use of present UTP system components. Demands for higher frequencies, more bandwidth and improved systems (e.g., Ethernet 1000Base-T) on UTP cabling, render existing systems and methods unacceptable. The TIA/EIA category 6 draft addendum related to new category 6 cabling standards illustrates heightened performance demands. For frequency bandwidths of 1 to 250 MHz, the draft addendum requires the minimum NEXT values at 100 MHz to be −39.9 dB and −33.1 dB at 250 MHz for a channel link, and −54 dB at 100 MHz and −46 dB at 250 MHz for connecting hardware. Increasing the bandwidth for new category 6 (i.e., from 1 to 100 MHz in category 5 to 1 to 250 MHz in category 6) increases the need to review opportunities for further reducing system noise.
Moreover, the TIA/EIA 568 category 6A draft-addendum for new Augmented Category 6 cabling standards for frequency bandwidths of 1 to 500 MHz for a channel link are −54 dB at 100 MHz and −34 dB at 500 MHz for connecting hardware. The requirements for Return Loss for a channel are −12 dB at 100 MHz and −6 dB at 500 MHz and for a connector its −28 dB at 100 MHz and −14 dB at 500 MHz.
A particular aspect associated with connecting hardware in which compensation for NEXT and FEXT is needed is the electrical interface modular housing. In particular, it will be necessary to reduce the noise levels in this component to meet the Category 6 and 6A standards.
The standard modular jack housing is configured and dimensioned so as to provide maximum compatibility and matability between various manufacturers, e.g., based on the FCC part 68.500 mechanical dimension. Two types of offsets have been produced from the FCC part 68.500 modular jack housing dimensions.
Type one is the standard FCC part 68.500 style for modular jack housing and such standard housing does not add or include any compensation methods to reduce crosstalk noises. The standard modular jack housing utilizes a straightforward design approach and, by alignment of lead frames in a relatively uniform, parallel pattern, high NEXT and FEXT are produced for certain adjacent wire pairs.
This type one or standard FCC part 68.500 style of modular jack housing connector is defined by two lead frame section areas. The first section is the matable area for electrical plug contact and section two is the output area of the modular jack housing. Section one aligns the lead frames in a relatively uniform, parallel pattern from lead frame tip to the bend location that enters section two, thus producing high NEXT and FEXT noises. Section two also aligns the lead frames in a relatively uniform, parallel pattern from lead frame bend location to lead frame output, thus producing and allowing additional high NEXT and FEXT noises.
Approaches exist that are intended to reduce the crosstalk noises associated with these type one or standard modular jack housings. For example, U.S. Pat. No. 6,139,371 to Troutman et al. discloses an electrical connector having an irregular bend in two lead frame of each pair frontal elongated plates and parallel at the free end of pins 3 to 5 and pins 4 to 6. This added coupling reduces crosstalk ineffectively since the elongated plates are crossed overlapped and also adjacent thus creating unwanted parallelisms 3 to 4 and 5 to 6 which increase crosstalk noises, thus becoming less effective. Although crosstalk noise may be reduced, forming lead frames with paralleled elongated plates in such a disclosed manner, may substantially increase the effective complex modes of coupling. This may potentially increase NEXT, FEXT and noise variation factors.
A further approach to reduction of crosstalk noise associated with a modular housing is described by U.S. Pat. No. 6,332,810 to Bareel. The Bareel '810 patent discloses an electrical connector having irregular bends in all 8 lead frames of each pair. Frontal coupling plates are provided on contacts 1, 3, 4, 5, 6 and 8. The coupling plates are vertically aligned and are feature an arrangement order of P1, P3, P5, P4, P6 and P8 in a housing. Positions 4 and 5 are more adjacent and are constructed on a spring beam contact with curved based portions. The metallic vertical plates are orthogonal of the plane formed by the plurality of terminals. Although crosstalk noise may be reduced, forming lead frames with elongated plates arranged in the disclosed parallel manner may substantially increase the effective complex modes of coupling, which may potentially increase NEXT, FEXT and noise variation factors.
U.S. Pat. No. 6,176,742 to Arnett et al. discloses an electrical connector having wire contacts constructed on elongated curved spring beam portions. The ends of the spring beam contacts are electrically tapped to an external capacitive arrangement of metallic plates on position 3 to 5 and 4 to 6. Positions 4 and 5 are more adjacent to a pair engaged by a mated plug. The design of the Arnett '742 patent can undesirably decrease contact flexibility which adds complexity to design. In addition, utilizing a curved spring beam contact design can increase unwanted NEXT/FEXT noises because of the adjacencies between pairs.
U.S. Pat. No. 6,443,777 to McCurdy et al. discloses an electrical connector having wire contacts constructed in an elongated wire contact arrangement. The free ends of the elongated wire contacts are electrically tapped to an external capacitive arrangement on a printed circuit board (“PCB”) for positions 3 to 5 and 4 to 6, and are engaged by a mated plug.
U.S. Pat. No. 5,618,185 to Aekins discloses a further approach to noise reduction. The subject matter of the Aekins '185 patent is hereby incorporated by reference herein in its entirety for all purposes. The Aekins '185 patent describes a connector for communications systems that includes four input terminals and four output terminals in ordered arrays. A circuit electrically couples respective input and output terminals and cancels crosstalk induced across adjacent connector terminals. The circuit includes four conductive paths between the respective input and output terminals. Sections of two adjacent paths are in close proximity and cross each other between the input and output terminal. At least two of the paths have sets of vias connected in series between the input and output terminals. The sets of vias are adjacent.
Despite efforts to date, a need remains for inserts/connector systems and associated methods that offer enhanced noise reduction. These and other needs and/or limitations are addressed and/or overcome by the systems, assemblies and methods of the present disclosure.